Either the one with Dumbo turning rogue in his later years, terrorizing the airlines, or the one viewed from inside the pet store - with a pirahana in a goldfish bowl and the cat with two wooden legs. Runners up:

Polar bears eating an igloo: "I just love these things! Crunchy on the outside and a chewy center!"

Bears at abandoned car, one holding a hubcap to his ear: "I can hear the traffic!"